Fix for my #1 Thunderbird headaches

I love Thunderbird as my e-mail client but there are two main grievances I have with it:
* it's always ticked me off that you can make it show messages threaded, but if you click on any of the columns to sort your messages it immediately goes back to unthreaded. It then takes three clicks to get it back to threaded.
* the default sort order for date should be chronological (so new items show at the top)

Today I can scratch both of those off the list, though only one with partial success. Mozilla blogger Chris Ilias documents the buried preference key that keeps the threaded view showing. You have to set the value of 'mailnews.thread_pane_column_unthreads' to false (under Tools->Options->Advanced->General->Config Editor).

As for making every folder displays in reverse chronological order by default, I was inspired by Chris' preference digging and found the right preferences:
* mailnews.default_sort_order: set to 2 (1 is ascending, 2 is descending)
* mailnews.default_sort_type: should already be set to 18 (date).

It's hard to tell if setting this key works because it doesn't retroactively apply to existing folders -- you're stuck having to fix their sort order manually. But in the future, this will be one of the first keys I switch when I install Thunderbird.

You can find more documentation of the sort preferences buried in this Bugzilla thread, though the author reverses the sortorder and sorttype documentation and not all of the preferences mentioned are in the release.